Electromagnetic launchers (EML), commonly referred to as railguns, operate by generating projectile motion through an electromagnetic force known as Lorentz force. A conventional electromagnetic launcher comprises a first conducting rail and a second conducting rail that are oriented parallel to each other as well as a direct current (DC) power supply that is connected to one end of each conducting rail. Two currents travel in opposite directions to each other through the first conducting rail and the second conducting rail. A sliding conductive armature bridges the gap in between the two conducting rails and remains in contact with the two conducting rails, completing the circuit. A projectile is placed in between the conducting rails and is driven by the conductive armature. The conductive armature may be integral to the projectile. Lorentz force is generated by the interaction between the electric current in the accelerated sliding armature and the magnetic induction field (B-field) generated by the flow of current in the closed loop. Because the electric current in the conductive armature and the B-field are oriented at a right angle relative to each other, the Lorentz force is maximized and oriented normal to the plane of electric current and B-field intensity. As such, the projectile is launched in a straight line parallel to the pair of conducting rails at a high muzzle velocity suitable for straight free flight.
Electromagnetic accelerators are particularly notable in military applications due to the much greater achievable muzzle velocities relative to conventional firearms using chemical propellants. However, there are several drawbacks that are inherent to the aforementioned mechanism used by conventional electromagnetic launchers. One such drawback is the energy loss and inefficiency due to mechanical friction between the conducting rails and the conductive armature, electric arcing due to increasing distance between the conducting rails, and thermal expansion of the conducting rails and the projectile. Proper heat dissipation is particularly important as well as extreme heat may result in degradation of equipment material and system failure during operation.
The present invention is a dynamic B-field accelerator that addresses the drawbacks that are inherent to conventional electromagnetic accelerators. The present invention eliminates the need for the conductive armature in between the conducting rails. In lieu of the conductive armature, the present invention implements a power supply and a solenoid coil with ferromagnetic core that are integrated into a projectile that is positioned in between a pair of conducting rails. Electric current within the conducting rails travels from the first conducting rail to the second conducting rail through an upper conducting sheet above the projectile and a lower conducting sheet below the projectile. The coil is offset by a short distance above the plane of the lower conducting sheet and a short distance below the plane of the upper conducting sheet, enabling the coil to move. Lorentz force is generated by the interaction of the current in the conducting sheet directly under the coil with the central B-field generated by the current within the coil. External magnetic induction outside the coil is present in the opposite direction to the central B-field. However, the central B-field is much stronger than the external magnetic induction, in essence negating the external magnetic induction in both force and direction.